The whole art of making experiments in chemistry is founded on the principle: we must always suppose an exact equality or equation between the principles of the body examined and those of the products of its analysis.

In performing experiments, it is necessary... that they be simplified as much as possible, and that every circumstance that could complicate the results should be completely removed.

Imagination, on the contrary, which is ever wandering beyond the bounds of truth, joined to self-love and that self-confidence we are so apt to indulge, prompt us to draw conclusions which are not immediately derived from facts.

Nothing is lost, nothing is created, everything is transformed

Vegetation is the basic instrument the creator uses to set all of nature in motion.

Experiments upon vegetation give reason to believe that light combines with certain parts of vegetables, and that the green of their leaves, and the various colors of flowers, is chiefly owing to this combination.

The art of drawing conclusions from experiments and observations consists in evaluating probabilities and in estimating whether they are sufficiently great or numerous enough to constitute proofs. This kind of calculation is more complicated and more difficult than it is commonly thought to be. . . .